Re: Reallife szenario for GEQO

From: Bernd Helmle <mailings(at)oopsware(dot)de>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Reallife szenario for GEQO
Date: 2004-01-13 12:16:43
Message-ID: 4003E1AB.2040105@oopsware.de
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Richard Huxton wrote:
> On Tuesday 13 January 2004 09:50, Bernd Helmle wrote:
>
>
>
> I don't think it's that it provides a better plan, just that it comes up with
> a quicker solution. Searching all possible paths is not practical for a large
> number of tables, so you need another approach.
>

Aggreed. That was my opinion, too. Sorry for my unclear statement.

> Google for "travelling salesman problem" for discussion of the sort of
> thinking behind it.
>

That was the first thing i've done. I understand the theoretical
background, but i need a practical scenario, to show:

QUERY A with GEQO
QUERY A without GEQO

And then compare the specific query plan generation efficency.

In this case I have to think about a practical database scenario, to
execute such queries. If i have enough tables i can join against, i
should see an improvement, in theory.

But what means "enough tables"?

So i wonder, if anyone had done such a comparison already.

Thanks for your reply,

Bernd

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